As wireless communication systems such as cellular telephone, satellite, and microwave communication systems become widely deployed and continue to attract a growing number of users, there is a pressing need to accommodate a large and variable number of communication subsystems transmitting a growing volume of data with a fixed resource such as a fixed channel bandwidth accommodating a fixed data packet size. Traditional communication system designs employing a fixed resource (e.g., a fixed data rate for each user) have become challenged to provide high, but flexible, data transmission rates in view of the rapidly growing customer base.
The Third Generation Partnership Project Long Term Evolution (“3GPP LTE”) is the name generally used to describe an ongoing effort across the industry to improve the universal mobile telecommunications system (“UMTS”) for mobile communications. The improvements are being made to cope with continuing new requirements and the growing base of users. Goals of this broadly based project include improving communication efficiency, lowering costs, improving services, making use of new spectrum opportunities, and achieving better integration with other open standards and backwards compatibility with some existing infrastructure that is compliant with earlier standards. The project envisions a packet switched communications environment with support for such services as Voice over Internet Protocol (“VoIP”) and Multimedia Broadcast/Multicast Services (“MBMS”). MBMS may support services where base stations transmit to multiple user equipment simultaneously, such as mobile television or radio broadcasts, for example. The 3GPP LTE project is not itself a standard-generating effort, but will result in new recommendations for standards for the UMTS.
The UMTS Terrestrial Radio Access Network (“UTRAN”) includes multiple Radio Network Subsystems (“RNS”), each of which contains at least one Radio Network Controller (“RNC”). However, it should be noted that the RNC may not be present in the actual implemented systems incorporating Long Term Evolution (“LTE”) of UTRAN (“E-UTRAN”). LTE may include a centralized or decentralized entity for control information. In UTRAN operation, each RNC may be connected to multiple Node Bs which are the UMTS counterparts to Global System for Mobile Communications (“GSM”) base stations. In E-UTRAN systems, the eNode B may be, or is, connected directly to the access gateway (“aGW,” sometimes referred to as the services gateway “sGW”). Each Node B may be in radio contact with multiple UE devices (generally, user equipment including mobile transceivers or cellular phones, although other devices such as fixed cellular phones, mobile web browsers, laptops, PDAs, MP3 players, and gaming devices with transceivers may also be UE) via the radio Uu interface.
The wireless communication systems as described herein are applicable to, for instance, 3GPP LTE compatible wireless communication systems and of interest is an aspect of LTE referred to as “evolved UMTS Terrestrial Radio Access Network,” or E-UTRAN. In general, E-UTRAN resources are assigned more or less temporarily by the network to one or more UE devices by use of allocation tables, or more generally by use of a downlink resource assignment channel or physical downlink control channel (“PDCCH”). LTE is a packet-based system and, therefore, there may not be a dedicated connection reserved for communication between a UE and the network. Users are generally scheduled on a shared channel every transmission time interval (“TTI”) by a Node B or an evolved Node B (“eNode B”). A Node B or an eNode B controls the communications between user equipment terminals in a cell served by the Node B or eNode B. In general, one Node B or eNode B serves each cell. A Node B may be referred to as a “base station.” Resources needed for data transfer are assigned either as one time assignments or in a persistent/semi-static way. The LTE, also referred to as 3.9G, generally supports a large number of users per cell with quasi-instantaneous access to radio resources in the active state. It is a design requirement that at least 200 users per cell should be supported in the active state for spectrum allocations up to 5 megahertz (“MHz”), and at least 400 users for a higher spectrum allocation.
The types of UEs the E-UTRAN environment can accommodate are many. One type of UE service that is presently proposed to be supported in E-UTRAN systems is a UE that includes support for one or more closed subscriber groups (“CSG”). A closed subscriber group, for purposes of this application, is a group of one or more cells (eNode B stations, or base stations) on which the access is restricted to a limited group of one or more users, and which is not generally available for “public” access on the network. This type of UE, when registering with eNode B devices, can communicate with certain eNode B stations that are available only to a limited group of UE devices. Examples include arranging an eNode B in a residence, office, apartment building, or area so that only certain subscriber group UEs may register with and communicate with the eNode B station (typically referred to as a “cell”). A single UE may be a member of multiple CSGs. A single cell may support multiple CSGs. The need to accommodate the CSG functions in the environment poses several problems for the system. A need thus exists for methods and apparatus to efficiently support the CSG functions for eNode Bs and UEs in the E-UTRAN environment. The addition of support for CSG must have a minimum impact on the efficiency and operation of the remaining services in the environment, the other UEs, the eNode B devices, and mobile management entities (“MMEs”).